The invention relates to a drum hoist having a driven main shaft, at least one movable drum which is arranged on the main shaft with a locking brake, a coupling apparatus for the releasable connection of the movable drum and the main shaft, which drum hoist has a drum wheel with an internal toothing system, which drum wheel is connected fixedly to the movable drum so as to rotate with it, a shaft wheel with an external toothing system, which shaft wheel is connected fixedly to the main shaft so as to rotate with it, a coupler wheel with an external toothing system and an internal toothing system which can be displaced axially in an engagement and a disengagement direction on the external toothing system of the shaft wheel, a sliding ring which is connected fixedly on the end side to the coupler wheel so as to rotate with it, and a switching apparatus which is arranged fixedly on the frame of the drum hoist for displacing the sliding ring in an engagement and disengagement direction, it being possible for the external toothing system of the coupler wheel to be brought into engagement with the internal toothing system of the drum wheel by way of the axial displacement in the engagement direction and to be brought out of engagement by way of the axial displacement in the disengagement direction. Moreover, the invention relates to a method for engaging and disengaging a coupling apparatus of a drum hoist of this type.
In a drum hoist, a cable drum is used as cable carrier, onto which cable drum the conveying cable is wound or from which cable drum said conveying cable is unwound. A distinction is made between single drum hoists and double drum hoists. Double drum hoists can be configured, for example, as Blair hoists or bobbins. There are double drum hoists both with a fixed drum and a movable drum and with two movable drums. Here, the movable drums are connected releasably to the main shaft via a switchable coupling, the coupling apparatus. It is necessary for every movable drum of the drum hoist that there is a separate brake for the movable drum for coupling.
The winding direction of the cable on the drums of the double drum hoist is opposed, with the result that the cable of one drum is wound up and the other is unwound in an identical rotational direction of the main shaft.
Both drums can be offset relative to one another in the circumferential direction with the aid of the coupling apparatus. To this end, the movable drum is blocked by way of the brake which is assigned to it, and is decoupled from the further drum, in particular a fixed drum. As a result, the movable drum does not corotate during positioning of the second conveying means with the aid of the further drum. After the second conveying means is positioned at the desired location, the movable drum is coupled to the drive shaft again and the brake is released. Double drum hoists with coupling apparatuses therefore make conveying from different depths possible, with the result that, for example, one conveying means is loaded underground while the other is unloaded aboveground at the same time. This function is important, in particular, during the drilling of a shaft, since the depth of the shaft changes permanently here, in order to convey excavated material, for example, or to perform work in the shaft during the drilling. Here, particular value is placed on a rapid coupling operation with high reliability in terms of function, operation and availability.
The prior art of a coupling apparatus for a drum hoist from 1987 supplied by the company Gutehoffnungshütte, Aktienverein für Bergbau and Hüttenbetrieb (GHH for short) will be explained in greater detail using the partial section through a coupling apparatus of FIG. 1. (The designations which are present in the description of the prior art relate exclusively to FIG. 1.) An internally toothed drum wheel (1) is screwed to a side plate of a movable drum (not shown). Just like the fixed drum (not shown), a shaft wheel (2) is connected fixedly via flanges to the main shaft (not shown) so as to rotate with it. A coupler wheel (5), a sliding ring (6) and a switching element which is configured as a switching ring (7) are arranged axially displaceably on the external toothing system (4) of the shaft wheel (2). The switching ring (7) is connected fixedly to the frame on brackets, connected to the foundation of the double drum hoist, for the hydraulic displacing cylinders (not shown). The switching ring (7) slides in a circumferential groove (8) of the sliding ring (6), whereas the movable drum (not shown) rotates in the engaged state of the coupling apparatus. The engagement and disengagement of the coupling apparatus takes place at the standstill of the double drum hoist secured by brakes. Here, the hydraulic displacing cylinders secure the position of the coupler wheel (5) which can be displaced axially in the engagement and disengagement direction on the external toothing system (4) of the shaft wheel (3).
During operation of the known coupling apparatus for a double drum hoist, the problem has occurred in the majority of the double drum hoists that the coupler wheel (5) moved in the disengagement direction during the rotation and conveying with the movable drum, as a result of which considerable forces were exerted on the hydraulic displacing cylinders and on the switching ring (7) which is provided with sliding metal (9) on the end side. As a consequence, the grease lubrication between the groove (8) of the sliding ring (6) and the sliding metal (9) failed as a result of overheating, and the sliding metal (9) subsequently melted. It was never possible to determine the reason for this disengagement of the coupler wheel (5) under load of the movable drum in said double drum hoists. One possible approach to explain this was tumbling movements of the side plate on the drum wheel.
In order to avoid the movement in the disengagement direction under load of the movable drum, screws or bolts were installed retrospectively on the shaft wheel (2), which screws or bolts prevented an axial displacement of the coupler wheel. The coupling operation therefore requires that a mechanic first of all removes the retrospectively installed screws or bolts in a time-intensive manner, and ends with the mechanic subsequently attaching the elements again. Assembly steps of this type are not acceptable for the operation of a drum hoist with a coupling apparatus, in particular in drilling operation with frequent coupling operations.
DE 922 194 B discloses a drum hoist having a coupling apparatus, in which a movable drum which is provided with a brake can be coupled to a driven main shaft. A displacement sleeve with an external toothing system is attached as coupler device on a grooved part of the drive shaft. The external toothing system can be brought into and out of engagement with an internal toothing system of an intermediate part which is connected fixedly to the movable drum so as to rotate with it, by way of displacement of the displacement sleeve in the axial direction of the drive shaft. The displacement of the displacement sleeve takes place by way of a movement device which is installed on the drum shaft.